The Dynamat (labeled my pics wrong) is sound insulation as well as thermal insulation. A lot of people swear by it and I know a few professional builders that use it on all of their builds (non-concourse that is) that are to be driven. The stuff is kind of spendy $300 to do the entire cabin minus the roof. I had the headliner done before I decided to put the dyamate down. I will do the trunk some day after I get the car on the road again. I bought mine from Amazon best price by far. I like to buy local but at half the price, on the web, I just couldn’t justify it this time around. Read the reviews there lots of good information on what to do and what not to do. I did a lot of research before doing this and from what I can tell it is worth it. Most of the people that were unhappy from their results didn’t seem to spend the time to do it right. This is my first experience with it and I have no proof of a benefit yet, maybe by late June when the car gets on the road.